Propeller pitch change actuation system

Abstract

A mechanical pitch lock includes a pitch lock screw (60) that simultaneously rotates within an actuator (42) while the actuator moves to change the pitch of a propeller blade (16). While rotating simultaneously with the motion of the pitch actuator, the pitch lock screw maintains a longitudinal position allowing the actuator to move. If the pitch lock screw does not rotate simultaneously with the actuator, the pitch lock screw moves longitudinally with the actuator until it abuts a projection 66 thereby preventing further movement by the actuator.

Having thus described the invention, what is claimed: 
     
       1. An apparatus for adjusting the pitch of a variable pitch propeller blade characterized by: an actuator for setting the pitch of said propeller blade said actuator having;   a rotatable screw for setting propeller pitch, a nut mounted for longitudinal motion along said screw as said screw is rotated,   means for connecting said nut to said propeller blade to adjust the pitch of the propeller blade as said screw rotates, and   a rotatable means mounted within said nut for locking the nut against longitudinal motion if the rotatable means is not rotating with the longitudinal motion of the nut and for allowing the nut to move longitudinally if the rotatable means is rotating with the longitudinal motion of the nut.   
     
     
       2. The apparatus of claim 1 further characterized by: first means for driving said rotatable screw;   second means for driving said rotatable means; and means for synchronizing said first and second means such that when either of said first means or said second means is driven, the other of said first or second means is also driven thereby ensuring that the rotatable means rotates simultaneously with the longitudinal motion of the nut.   
     
     
       3. The apparatus of claim 1 wherein said rotatable means is characterized by: a lock screw means rotatably mounted within said nut, for maintaining a longitudinal position while rotating simultaneously with the longitudinal motion of the nut, and for moving longitudinally while not rotating simultaneously with said nut; and   an abutment means for limiting said longitudinal motion of said lock screw means while said lock screw means is not rotating simultaneously with said nut.   
     
     
       4. The apparatus of claim 3 further characterized by: first means for driving said rotatable screw;   second means for driving said rotatable means; and   means for synchronizing said first and second means such that when either of said first means or said second means is driven, the other of said first or second means is also driven thereby ensuring that the rotatable means rotates simultaneously with the longitudinal motion of the nut.   
     
     
       5. The apparatus of claim 2 wherein said rotatable means is characterized by: a lock screw means rotatably mounted within said nut, for maintaining a longitudinal position while rotating simultaneously with the longitudinal motion of the nut, and for moving longitudinally while not rotating simultaneously with said nut; and   an abutment means for limiting said longitudinal motion of said lock screw means while said lock screw means is not rotating simultaneously with said nut.